Thin film batteries, such as thin film Li-ion batteries, in particular solid-state thin film Li-ion batteries, are gaining more and more interest. A thin film battery is composed of several electrochemical cells that are connected in series and/or in parallel to provide the required voltage and capacity. A battery cell is mainly composed of a cathode electrode and an anode electrode separated by an electrolyte, which enables ion transfer between the two electrodes.
For the fabrication of thin film batteries, several methods may be used, for example physical vapor deposition processes such as sputtering, or solution based processes such as sol-gel processes. The different components (anode, electrolyte, and cathode) of such batteries are typically prepared separately, for example by hydrothermal powder synthesis. Complex compounds may be prepared by ball milling induced solid-state reaction. Such methods involve time-consuming processes. Several heating treatments are needed to obtain the desired material precursors in a powder-like form. These precursors are the basis for creating the separate components of the battery. Additional process steps such as dispersion, mixing and/or drying are needed to obtain mixed powders with a targeted stoichiometric composition.
One of the obstacles for the implementation of Li-ion based batteries in portable consumer electronics is the lack of process compatibility with CMOS processing. Generally, the presence of Li containing species inside CMOS processing facilities poses contamination issues.